1. Field of the Invention
The present invention relates to a method for suppressing or preventing symptoms of the human condition known as jet lag. Specifically, the invention is directed to a new use of 5-methoxypsoralen and related furocoumarin compounds.
2. Description of Prior Art and Other Published Information
Jet lag is a known psychological dislocation and disruption of bodily rhythms caused by high-speed travel across several time zones, usually in a jet airplane. In the course of such travel, the body's circadian clock is disturbed by the juxtaposition of night and day, or by merely a shift (usually of three hours or more) in the normal daily schedule to which the body is accustomed. Jet lag may cause a variety of maladies ranging from temporary exhaustion, insomnia, nausea and other, including gastrointestinal, ailments. Jet lag sufferers may experience a reduced desire and capacity to work or to pursue recreational activities and other normal functions usually associated with long-distance travel.
It is known that melatonin (N-acetyl-5-methoxytryptamine) is a sleep-inducing hormone secreted by the human pineal gland. Human melatonin secretion has a diurnal cycle with highest levels during the hours of darkness, typically peaking at about 11:00 p.m. (2300 hours), and reaching its lowest levels at about 7:00 a.m., or 0700 hours.
The linear furocoumarin, 5-methoxypsoralen, or 5-MOP, is well-known for its use in the treatment of various forms of psoriasis and other dermatoses such as vitiligo, atypical eczema and fungoid mycosis, and has been recognized as being especially useful in view of its efficacy and low toxicity. 5-MOP is also known for its beneficial effects in promoting "sun-tanning," or the browning of human skin as a result of the action of ultra-violet rays on the melanocytes of the skin, as described in Goupil, "Sun Products," U.S. Pat. No. 4,699,781.
Other furocoumarins have also been well-known for various uses, usually in the treatment of various skin conditions.
In a controlled study, 5-MOP (given orally in doses of 40 mg. to normal subjects at 2100 hours) increased the plasma level of melatonin from the second hour after administration. Increased secretion was greater after evening than after morning administration, as reported by Souetre, E. et al., "5-Methoxypsoralen Increases The Plasma Melatonin Levels In Humans," J. Invest. Derm., vol. 89:152-155 (1987).
Until the present invention, 5-MOP has not been known to constitute an effective preventive or suppressive medication for the symptoms of jet lag.